[Mesa-dev] ARB_enhanced_layouts packing support for i965 Gen8+

[Timothy Arceri]

There are a number of packing tests already in piglit but I have a few
more on the way.

This series does not add support for doubles as there is currently a
doubles bug with explicit locations that I've pointed out to the Igalia
guys. Samuel is working on a fix for this after which I will finish
up the doubles support.